Re: [PATCH 6/6] drm/i915/gvt: use gfn_to_pfn's page instead of pfn

Please ignore this last patch. It was put together as an afterthought and wasn't properly tested.

-David

On Thu, Jun 24, 2021 at 12:59 PM David Stevens stevensd@chromium.org wrote:

Return struct page instead of pfn from gfn_to_mfn. This function is only used to determine if the page is a transparent hugepage, to enable 2MB huge gtt shadowing. Returning the page directly avoids the risk of calling pfn_to_page on a VM_IO|VM_PFNMAP pfn.

This change also properly releases the reference on the page returned by gfn_to_pfn.

Signed-off-by: David Stevens stevensd@google.com

drivers/gpu/drm/i915/gvt/gtt.c | 12 ++++++++---- drivers/gpu/drm/i915/gvt/hypercall.h | 3 ++- drivers/gpu/drm/i915/gvt/kvmgt.c | 12 ++++-------- drivers/gpu/drm/i915/gvt/mpt.h | 8 ++++---- 4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c index 9478c132d7b6..b2951c560582 100644 --- a/drivers/gpu/drm/i915/gvt/gtt.c +++ b/drivers/gpu/drm/i915/gvt/gtt.c @@ -1160,16 +1160,20 @@ static int is_2MB_gtt_possible(struct intel_vgpu *vgpu, struct intel_gvt_gtt_entry *entry) { struct intel_gvt_gtt_pte_ops *ops = vgpu->gvt->gtt.pte_ops;

•   unsigned long pfn;
  

•   struct page *page;
  

•   bool is_trans_huge;
  
    if (!HAS_PAGE_SIZES(vgpu->gvt->gt->i915, I915_GTT_PAGE_SIZE_2M))
            return 0;
  
  

•   pfn = intel_gvt_hypervisor_gfn_to_mfn(vgpu, ops->get_pfn(entry));
  

•   if (pfn == INTEL_GVT_INVALID_ADDR)
  

•   page = intel_gvt_hypervisor_gfn_to_mfn_page(vgpu, ops->get_pfn(entry));
  

•   if (!page)
            return -EINVAL;
  
  

•   return PageTransHuge(pfn_to_page(pfn));
  

•   is_trans_huge = PageTransHuge(page);
  

•   put_page(page);
  

•   return is_trans_huge;
  

}

static int split_2MB_gtt_entry(struct intel_vgpu *vgpu, diff --git a/drivers/gpu/drm/i915/gvt/hypercall.h b/drivers/gpu/drm/i915/gvt/hypercall.h index b79da5124f83..017190ff52d5 100644 --- a/drivers/gpu/drm/i915/gvt/hypercall.h +++ b/drivers/gpu/drm/i915/gvt/hypercall.h @@ -60,7 +60,8 @@ struct intel_gvt_mpt { unsigned long len); int (*write_gpa)(unsigned long handle, unsigned long gpa, void *buf, unsigned long len);

•   unsigned long (*gfn_to_mfn)(unsigned long handle, unsigned long gfn);
  

•   struct page *(*gfn_to_mfn_page)(unsigned long handle,
  

•                                   unsigned long gfn);
  
    int (*dma_map_guest_page)(unsigned long handle, unsigned long gfn,
                              unsigned long size, dma_addr_t *dma_addr);
  

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c index b829ff67e3d9..1e97ae813ed0 100644 --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -1928,21 +1928,17 @@ static int kvmgt_inject_msi(unsigned long handle, u32 addr, u16 data) return -EFAULT; }

-static unsigned long kvmgt_gfn_to_pfn(unsigned long handle, unsigned long gfn) +static struct page *kvmgt_gfn_to_page(unsigned long handle, unsigned long gfn) { struct kvmgt_guest_info *info; kvm_pfn_t pfn;

    if (!handle_valid(handle))

•           return INTEL_GVT_INVALID_ADDR;
  

•           return NULL;
  
    info = (struct kvmgt_guest_info *)handle;
  
  

•   pfn = kvm_pfn_page_unwrap(gfn_to_pfn(info->kvm, gfn));
  

•   if (is_error_noslot_pfn(pfn))
  

•           return INTEL_GVT_INVALID_ADDR;
  

•   return pfn;
  

•   return gfn_to_pfn(info->kvm, gfn).page;
  

}

static int kvmgt_dma_map_guest_page(unsigned long handle, unsigned long gfn, @@ -2112,7 +2108,7 @@ static const struct intel_gvt_mpt kvmgt_mpt = { .disable_page_track = kvmgt_page_track_remove, .read_gpa = kvmgt_read_gpa, .write_gpa = kvmgt_write_gpa,

•   .gfn_to_mfn = kvmgt_gfn_to_pfn,
  

•   .gfn_to_mfn_page = kvmgt_gfn_to_page,
    .dma_map_guest_page = kvmgt_dma_map_guest_page,
    .dma_unmap_guest_page = kvmgt_dma_unmap_guest_page,
    .dma_pin_guest_page = kvmgt_dma_pin_guest_page,
  

diff --git a/drivers/gpu/drm/i915/gvt/mpt.h b/drivers/gpu/drm/i915/gvt/mpt.h index 550a456e936f..9169b83cf0f6 100644 --- a/drivers/gpu/drm/i915/gvt/mpt.h +++ b/drivers/gpu/drm/i915/gvt/mpt.h @@ -214,17 +214,17 @@ static inline int intel_gvt_hypervisor_write_gpa(struct intel_vgpu *vgpu, }

/**

• • intel_gvt_hypervisor_gfn_to_mfn - translate a GFN to MFN

• • intel_gvt_hypervisor_gfn_to_mfn_page - translate a GFN to MFN page
  • @vgpu: a vGPU
  • @gpfn: guest pfn
  • Returns:

• • MFN on success, INTEL_GVT_INVALID_ADDR if failed.

• • struct page* on success, NULL if failed.
  */

-static inline unsigned long intel_gvt_hypervisor_gfn_to_mfn( +static inline unsigned long intel_gvt_hypervisor_gfn_to_mfn_page( struct intel_vgpu *vgpu, unsigned long gfn) {

•   return intel_gvt_host.mpt->gfn_to_mfn(vgpu->handle, gfn);
  

•   return intel_gvt_host.mpt->gfn_to_mfn_page(vgpu->handle, gfn);
  

}

/**

2.32.0.93.g670b81a890-goog